Thanks for posting this. I've had some excellent service from my 3.0 Corvair since 2012. In the nearly 20 years that I've been looking at Corvair conversions I've watched a number of engine conversion "gurus" fall by the wayside either from trying to sell a poorly thought out conversion or being less than honest with the folks they want as customers. There is a reason William has been successful for 30 years with Corvairs.
Take your pick of several choices reviewed on this channel - Engines Week 2020 feature:
Edge Performance Yamaha
(and hopefully more engines on the way)